News 27 September 2001

A summary of technological developments in the past week

As the rescue and recovery efforts at the World Trade Center continue, electrotechnology adapted for this purpose is helping to save lives by giving searchers the lay of the land, telling them where it’s safe to tread, and in several instances, standing in for them in places where sending in a human would be unwise or simply impossible.

In the days after the 11 September attack, despite choking plumes of smoke that prevented a visual survey of the wreckage, a twin propeller plane flying 1500 meters above lower Manhattan began making topographic images of the site where the Twin Towers once stood. The plane is equipped with lidar, a laser-based instrument similar to radar that sends pulses of light (instead of radio waves) to a target and measures the time it takes for each beam to be reflected. The device emits 15 000 laser pulses a second, from which EarthData International Inc., Fresno, Calif., the company collecting the data, plots 100 000 points–some as much as 9 meters below street level. The data generated by the lidar system, when combined with information from an on-board global positioning device that tracks the plane’s exact location and altitude, yields topographical information accurate to within 152.4 mm.

The data, collected on an ongoing basis since the attack, has been studied by researchers at the Center for the Analysis and Research of Spatial Information at nearby Hunter College of the City University of New York. The research is being used to produce three-dimensional maps identifying mounds of debris and voids, as well as areas where shifts or collapses are likely to occur.

The lidar-carrying plane has also been outfitted with equipment that measures heat, so rescue teams can track underground fires that continue to smolder and flare up when the debris covering them (and limiting their access to oxygen) is removed.

Also on hand shortly after the attacks were more than a dozen remote-controlled robots that used lights, video cameras, two-way audio, and night vision to give rescue teams an idea of where to search, as well as an up-close glimpse of the obstacles separating them from any survivors. The machines–mostly prototypes financed by the U.S. National Science Foundation, the Office of Naval Research, and the Tactical Mobile Robots program run by the U.S. Department of Defense’s Advanced Research Projects Agency–are designed to traverse the small openings between the steel girders and chunks of concrete in various ways. Some, small enough to fit into sewer pipes less than 305 mm in diameter, can get into even tighter spaces by flattening themselves. Others are adept at standing upright to "see" over obstacles, or using flippers to climb stairs or uneven hills.

The robots range in cost from US $15 000 to $30 000, depending on their sophistication and the number of sensors on board. Many, including the MicroTrac crawler that on 12 September located a pocket of rooms where bodies were later discovered, are customized versions of commercially available machines.

Just as important to the work proceeding at ground zero is the effort to ensure the safety of the people on-site by making sure that neighboring buildings damaged by the collapse of World Trade Center Buildings One, Two, and Seven do not pose a danger. Of particular interest is World Trade Center Building 4, a nine-story structure that engineers from the U.S. Federal Emergency Management Agency (FEMA) noticed was shifting to a degree that suggested it might collapse as well.

To keep a constant eye on its status, FEMA called on James Sabatier, a researcher at the U.S. Army Night Vision Electronic Sensors Directorate’s Laboratory at Fort Belvoir, Va. Sabatier has developed a laser system he hopes will someday accurately detect the presence of landmines by measuring the differences in ground vibrations depending on whether a buried object is present. He quickly adapted this device to measure changes in Building 4’s bearing. Powered by a gasoline generator, the laser system bounces beams off the building’s facade every half second–a technique sensitive enough to keep track of movements on the order of a micrometer. "By this close, constant monitoring, we can let engineers know immediately if there are any big changes in the frequency and amplitude of the oscillation," said Sabatier, who has been working 12-hour shifts monitoring the equipment, which he set up some 46 meters from Building 4.

Privacy may be another casualty of attacks

With a minimum of debate and informed public opinion, the U.S. Congress is considering a number of ways to increase the powers of law enforcement. These include measures that could greatly increase on-line surveillance. Others would redefine many computer-related crimes, such as writing a computer virus, as terrorist acts. This change would potentially expand law enforcement’s authority when investigating such offenses, and increase the penalties for those convicted of them.

The most controversial element in President Bush’s proposal, dubbed the Anti-Terrorism Act of 2001 (ATA), is what the Electronic Privacy Information Center (EPIC), a Washington, D.C.—based cyber-rights advocacy group, calls a significant expansion in "law enforcement authority to use trap-and-trace and pen register devices."

Pen registers and trap-and-trace devices are used to record the phone numbers of calls made by a particular phone. There already is an electronic analog to this: the FBI has asserted the right to capture e-mail header information–to/from addresses and subject lines–and URLs of pages viewed by Web browsers with its so-called Carnivore system, now more innocuously named DCS1000.

DCS1000 is a computer placed on an Internet service provider’s network through which all of its network traffic is routed. Because all traffic is monitored, not just that of an individual suspect, civil rights activists, such as EPIC, argue that DCS1000 already constitutes a questionable expansion of law enforcement’s powers. The ATA would ratify the FBI’s interpretation of these prior statutes that govern trap-and-trace and pen-register—based surveillance.

The FBI argues that e-mail headers and URLs are much like phone numbers--they only indicate whom or what system an Internet user is contacting. Critics point out that e-mail subject lines are more like content than they are like addresses, and that URLs in particular can be quite specific--an Amazon.com URL might list a book’s title or an author’s name, for example. (Reading the content of an e-mail, like listening to an actual telephone conversation, requires a wiretap, for which the authorization requirements are much more stringent.)

Another controversy surrounds the so-called roving wiretap issue. Donald Rumsfeld, the U.S. secretary of defense, and other administration officials have made a point of noting that when a criminal suspect moves from one telephone-related system to another, a new authorization is needed for surveillance. According to the EPIC analysis, "Current law requires third parties (such as common carriers and others) ‘specified in court-ordered surveillance’ to provide assistance necessary to accomplish the surveillance." ATA "would extend that obligation to unnamed and unspecified third parties." EPIC points out that such "generic" surveillance might fail to "comport with the Fourth Amendment’s requirement that any search warrant ‘particularly describe the place to be searched.’"

Many computer crimes, such as hacking or writing viruses, would be classified as terrorist acts by the ATA, with severe penalties attached–up to life imprisonment. The new, stiffer penalties are not limited to computer crimes; damaging a government building–even an act such as throwing a brick through a post office window–would be considered an act of terrorism.

Many in Congress, however, have urged their colleagues to exercise caution. Representative Robert L. Barr Jr. (R-Ga.), pointed out that law enforcement has long sought many of the measures being considered, and is using the current circumstances to gain "authorities that it has been unable to obtain previously."

In a recent column in The Washington Post, Rep. John Conyers Jr. (D-Mich.) echoed the same theme. Recalling legislative considerations in the aftermath of the bombings of the World Trade Center in 1993 and of Oklahoma City in 1996, Conyers pointed out that many proposals had little to do with terrorism. He added, "Legislation that began in good faith as an effort to fine-tune our anti-terrorism laws turned into a legislative race to the bottom."

ATA generally avoids the difficult issue of cryptography. But in the U.S. Senate, Judd Gregg (R-N.H.) has drafted his own bill aimed at making encrypted data accessible to law enforcement. One measure would require key escrow. Most encryption systems for finance and communications use what is called public key cryptography, which employs a mathematically complex system involving a key that is split into public and private halves. Data encrypted with the public half can be decrypted by the private half, which is known only to the recipient. Sentor Gregg’s legislation would require that copies of private keys be stored with a government or other agency and made available to law enforcement by court order. Key escrow was first proposed by the Clinton administration in the mid-1990’s, but companies and consumer advocacy groups said no one would not use a product containing the so-called Clipper chip, which provided back-door government access. More importantly, they argued, the cache of escrowed keys would be a target of hackers and spies.

FCC: airwaves safe from 3G takeover

The U.S. Federal Communications Commission (FCC) announced on 24 September that it had voted unanimously to scrap a plan that would have taken the portion of the spectrum now used by organizations such as schools, health care facilities, and the military and given it to wireless telephone carriers to establish so-called third-generation wireless services. The agency, which had for months contemplated the reallocation of the 2500—2690 MHz band, said that instead it would attempt to include a mobile wireless component so that these frequencies can still be used for fixed wireless services such as Internet access, but also handle 3G services like music and video downloads and high-speed Internet.

Meanwhile, the FCC and the U.S. Department of Commerce are still searching for unoccupied airwaves to sell to the mobile phone companies.

Satellite radio broadcasting on the air

XM Satellite Radio Holdings Inc., Washington, D.C., became the first company to launch a satellite radio service when it debuted on 25 September in San Diego, Calif., and Dallas, Texas. Programming originates from XM’s Washington, D.C., studios and is transmitted via satellite to a network of ground stations that amplify the signal and transmit it to special radios that then unscramble it much like a set-top cable box does for television.

For a fee of $9.95 per month, the service offers listeners 100 stations to choose from: 71 will be music channels, with the remaining 29 devoted to news, sports, and talk. XM will also carry live simulcasts from CNBC, CNN Headline News, and C-SPAN. Special radios capable of acquiring the signal start at $225.

The launch came a week after the U.S. Federal Communications Commission granted XM and rival Sirius Satellite Radio Inc. (whose launch is scheduled for the end of the year) temporary approval to operate its repeater stations–a move strongly opposed by wireless telephone carriers, who argued that the service would interfere with their portion of the spectrum. The operating license is valid until 18 March 2002, but XM executives said they expect a final set of rules governing the repeaters to be in place before then.

The two-city launch is just a trial run, said XM chief executive Hugh Panero, who added that the service will be rolled out across the southwest and southeast by 18 October and nationwide by 15 November. According to Panero, when the service is up and running, "A driver traveling from San Diego to Washington, D.C., with an XM radio would have coverage for about 98 percent of the trip."

VeriSign buys Illuminet for $1.2 billion

VeriSign Inc., San Francisco, the leading Web address registry service, and a leader in authentication and payment security services for e-commerce, announced on 24 September its plan to acquire Illuminet Holdings Inc., Olympia, Wash., for $1.2 billion. The deal will accelerate VeriSign’s move into the location-based telephone services business–an early application in the emerging market for integrated voice and data services.

In acquiring Illuminet, VeriSign gains an independent carrier-to-carrier switching network that offers mobile phone users options like wireless roaming, short messaging, Internet telephony, and local number portability and lets them retain the same phone number under different carriers.

Earlier this year, the company announced its plans to start a Global Voice Registry, which will enable wireless phones to link specific phone numbers to Web addresses or domain names. In the near future, said a VeriSign spokesman, mobile phone users will be able to get information about a business or be connected to its nearest location by simply saying its name.